This is really good input. Thank you. I remember when I had the lid off
that there was a quarter size scorch mark on the inside of the lid and I
remember wondering how that happened. I will be sure to check this today.
I did get it to fail again just before dark last evening. I was able to fix
it by yanking and jerking the coax to the TH7. I am going to replace the
PL259 today.
Thank you, Pat,K8PC

I have an Ameritron RCS-8V which has been in service for almost 20 years.
Shortly after I purchased it new, I started having intermittant problems
similar to yours, especially in cold weather. This was the case until I
discovered the relay arms were touching the inside of the plastic cover
and
would only partially actuate. The cure was to place a couple of flat
washers between the plastic case the and the chassis in all four corners,
increasing the clearance between the case and the relays. It has operated
flawlessly ever since.

I would try operating the switch with the cover off to see how the relays
actuate.